Atomic coherence swing in a double-A-type system using ultraslow light

Using an ultraslow light-based double-A-type configuration we demonstrate atomic coherence swing between two different frequencies in a nondegenerate four-wave mixing scheme. A short control pulse applied to the middle of an ultraslow light envelope results in coherence conversion between two ground states, causing both coherence depletion and recovery, resulting in a temporal hole and amplification in the ultraslow light envelope. This outcome holds potential for temporally and spatially localized coherence control of ultraslow light in such applications as a selective photon trap. (C) 2009 Optical Society of America